A note on the smartReadFile function from gaosipov:

Change the indexes on the preg_match matches to:
      
      $begin = intval($matches[1]);
      if( !empty($matches[2]) ) {
        $end = intval($matches[2]);
      }

Otherwise the $begin would be set to the entire section matched and the $end to what should be the begin.

See preg_match for more details on this.